Acetylenic ethers

ABSTRACT

POLY(OXYPROPYLENE) AND POLY(OXYETHYLENE/OXYPROPYLENE) DERIVATIVES OF CERTAIN ACETYLENIC ALCOHOLS, A PROCESS FOR THEIR MANUFACTURE AND THEIR USE AS CORROSION-RESTRAINING COMPOUNDS IN ACID-PICKLING BATHS FOR FERROUS METALS. THE COMPOUNDS ARE PARTICULARLY SUITABLE FOR USE IN HYDROCHLORIC ACID BATHS AND THEY HAVE LITTLE TENDENCY TO FOAM.

United States Patent US. Cl. 260-615 B 1 Claim ABSTRACT OF THE DISCLOSURE Poly(oxypropylene) and poly(oxyethylene/oxypropylene) derivatives of certain acetylenic alcohols, a process for their manufacture and their use as corrosion-restraining compounds in acid-pickling baths for ferrous metals. The compounds are particularly suitable for use in hydrochloric acid baths and they have little tendency to foam.

This invention relates to corrosion restraining compounds and more particularly it relates to compounds for restraining the corrosion of ferrous metals in acid pickling baths.

Ferrous metals, such as steel, which are subjected to working at elevated temperatures during the course of manufacture become coated with a layer of oxide impurity, often referred to as mill scale. For many subsequent processing operations, such as coating or plating, it is necessary to remove the layer of oxide scale and it is usual to do this by treating the metal in a bath of aqueous acid, an operation referred to as acid pickling. The acids commonly used for this purpose are sulphuric acid and hydrochloric acid, although other acids such as phosphoric acid and sulphamic acid may be used. Once the layer of oxide scale is removed, the acid is free to attack the exposed metal surface and in order to reduce the attack on the metal itself as much as possible it is advantageous to add a corrosion restrainer to the acid pickling bath.

In some cases it is the practice in the industry to recover acid by removal of dissolved iron from the spent acid pickling liquors. This can be accomplished by various techniques but in all cases the liquors are severely agitated or sprayed and it is desirable that any additives to the pickling should not give rise to any appreciable amount of foam at this stage.

We have now found that polyoxyalkylene derivatives of certain acetylenic alcohols are particularly valuable corrosion restraining compounds for addition to acid pickling baths, and are especially suitable for use with hydrochloric acid pickling baths. 'In contrast to most of the parent acetylenic alcohols which are quickly removed from acid pickling baths by volatilisation, the oxyalkylene derivatives of this invention are relatively involatile and have a much longer lifetime in the acid pickling bath.

In addition, acid pickling baths incorporating the products of the present invention as corrosion restraining compounds show little tendency to foam, and this is particularly important when recovering hydrochloric acid from spent liquors for re-use.

According to the present invention there are provided polyalkylene derivatives of acetylenic alcohols having the general formula:

| RCCECH O (Y) 11H Formula I wherein R represents a straight chain or branched chain alkyl radical having from 1 to carbon atoms, R represents a hydrogen atom or an alkyl radical having from 1 to 10 carbon atoms, each Y represents either an oxyethylene group or an oxypropylene group, at least one Y being an oxypropylene group, and n is an integer of from 2 to 30.

As examples of the straight chain or branched chain alkyl radicals which are represented by R there may be mentioned methyl, ethyl, n-propyl, l-ethylpentyl, isopropyl, butyl, isobutyl, hexyl and heptyl, and as examples of the alkyl radicals which are represented by R there may be mentioned methyl, ethyl and butyl.

According to a further feature of the invention there is provided a process for the manufacture of polyoxyalkylene derivatives of acetylenic alcohols having the general Formula I above which comprises condensing an acetylenic alcohol having the formula RRC(OH)CECH wherein R and R have the meanings stated above, with propylene oxide or both ethylene oxide and propylene oxide in the presence of a catalyst.

In the case where both ethylene oxide and propylene oxide are used in the process, the alcohol of Formula I may be condensed with the two oxides in admixture, when the product will have a random poly(oxyethylene/oxypropylene)copolymer chain, or the oxides may be reacted in any desired sequence to give a product having a block copolymer chain.

As examples of suitable catalysts there may be mentioned tertiary amines, for example trimethylamine, triethylamine, dimethylcyclohexylamine, N,N,N,N-tetramethyl-ethylenediamine and 4-dimethylaminopyridine, alkali and alkaline earth metal hydroxides, for example sodium hydroxide, potassium hydroxide, and barium hydroxide, acids such as sulphuric acid and phosphoric acid, and Lewis acid catalysts, for example aluminium chloride, boron trifluoride either as such or as complexes such as the etherate, titanium tetrachloride and stannic chloride.

In most cases the reaction between the acetylenic alcohol and the propylene oxide or ethylene and propylene oxides is conveniently carried out at temperatures of from 70 C. to C., but lower or higher temperatures, for example from l0 C. to C. may be used if desired.

According to yet a further feature of the invention there is provided an acid pickling bath for ferrous metals which comprises an aqueous acid containing a polyoxyalkylene derivative of an acetylenic alcohol having the general formula:

I R(|3-CECH O (Y) ,H Formula I wherein R, R, Y and n have the meanings stated above.

The amount of corrosion restraining compound which is added to the acid pickling bath may be varied over wide limits but we prefer to add between 0.05% and 0.4% by weight of the compound calculated on the weight of commercial acid used. Thus in the case of hydrochloric acid we prefer to add from 1 lb. to 8 lbs. of compound per ton of 28% hydrochloric acid in the acid pickling liquors. The concentration of hydrochloric in the acid pickling bath is usually between 1% and 20% by weight.

In order to make up the acid pickling bath the compound is simply stirred into the pickling acid, which is then ready for use, or the compound may be added to the concentrated acid prior to dilution.

Pickling can be carried out at temperatures of from 10 C. to 95 C. in the case of a hydrochloric acid bath.

The compounds of the present invention are also effective in restraining the corrosion of ferrous metals under other conditions, for example in the in situ descaling of plant, in the acidisation of oil and water wells where hydrochloric acd is used to open or enlarge the limestone fissures and protection of the ferrous metal well casing is essential, and in degreasing plants which use highly chlorinated solvents. These solvents are liable to contain traces of hydrogen chloride which are very corrosive to the degreasing plant itself and to ferrous metal articles which are being degreased. Addition of a compound of the present invention to the degreasing solvent minimises the corrosive effect of any acid which may be present.

The invention is illustrated but not limited by the following examples, in which the parts and percentages are by weight.

EXAMPLE 1 3-methyl-1-butyn-3-ol (42 parts) and boron trifluoride etherate (1.5 parts) were stirred at 3040 C. while a mixture of ethylene oxide (60.5 parts) and propylene oxide (79.8 parts) was added. During the latter part of the addition the temperature was allowed to rise to 60 C. and was maintained at 60 C. for 1% hours on completion of the addition. After removal of volatile products at 60 C. and 20 mm. pressure the residual product was a light brown oil consisting of 161.1 parts of an adduct of methyl butynol with 4.68 molar proportions of ethylene oxide/propylene oxide in approximately 1:1 molar proportions.

EXAMPLE 2 The adduct of Example 1 (128.9 parts) and boron trifluoride etherate (1.2 parts) were stirred at 60 C. While a mixture of ethylene oxide (48.4 parts.) and propylene oxide (63.8 parts) were added. After stirring for a further 1 hour at 60 C. and removal of volatile products at 60 C. and 20 mm. pressure the residual product consisted of 218.9 parts of an adduct of methyl butynol with 9.09 molar proportions of ethylene oxide/propylene oxide in approximately 1:1 molar ratio.

EXAMPLE 3 An adduct of 3-methyl-1-pentyn-3-ol with 9.98 molar proportions of ethylene oxide/propylene oxide in an approximately 1:1 molar ratio (75.8 parts) and boron trifluoride etherate (0.45 part) were stirred at 60 C. while a mixture of ethylene oxide (18.2 parts) and propylene oxide (24 parts) was added. After stirring at 60 C. for 1 hour, followed by removal of volatile products at 60 C. and 20 mm. pressure the residual product consisted of 107.3 parts of an adduct of methyl pentynol with 14.92 molar proportions of ethylene oxide/propylene oxide in approximately 1:1 molar ratio.

EXAMPLE 4 1-hexyn-3-ol (49 parts) and boron trifluoride etherate (1.4 parts) were stirred at 30-40 C. while a mixture of ethylene oxide (60.5 parts) and propylene oxide (79.8 parts) was added. During the latter half of the addition the temperature was allowed to rise to 60 C. and was maintained at 60 C. for 1% hours following the addition. After removal of volatile products at 60 C. and 20 mm. pressure the residual product consisted of 179.9 parts of an adduct of hexynol with 5.13 molar proportions of ethylene oxide/ propylene oxide in approximately 1:1 molar ratio.

EXAMPLE 5 The adduct of Example 4 (89.9 parts) and boron trifluoride etherate (0.9 part) were stirred at 60 C while a mixture of ethylene oxide (36.3 parts) and propylene oxide (47.9 parts) was added. After subsequent treatment as in Example 2 the residual product consisted of 158.4 parts of an adduct of hexynol with 10.5 molar proportions of ethylene oxide/propylene oxide in approximately 1:1 molar ratio.

EXAMPLE 6 The adduct of Example 5 (79.2 parts) and boron trifluoride etherate (0.45 part) were stirred at 60 C. while a mixture of ethylene oxide (18.2 parts) and propylene oxide (24 parts) was added. After subsequent treatment as in Example 2 the residual product consisted of 111.7 parts of an adduct of hexynol with 15.6 molar proportions of ethylene oxide/propylene oxide in approximately 1:1 molar proportions.

EXAMPLE 7 1-hexyn-3-ol (32.7 parts) and boron tn'fiuoride etherate 0.4 =part) were stirred at 3040 C. while propylene oxide (57.4 parts) was added. The mixture was then stirred at 60-70 C. for 1% hours to complete the reactions and volatile products were removed at 60-65 C. under 15 mm. pressure. The residual product consisted of 88.6 parts of an adduct of hexynol with 3.21 molar proportions of propylene oxide.

EXAMPLE 8 The aduct of Example 7 (44.3 parts) and boron trifiuoride etherate (0.22 part) were stirred at 60 C. while propylene oxide (23.2 parts) was added. After further treatment as in Example 2 the residual product consisted of 66.8 parts of an adduct of hexynol with 5.8 molar proportions of propylene oxide.

EXAMPLE 9 4-ethyl-1-octyn-3-ol (61.6 parts) and boron trifluoride etherate (1.4 parts) were stirred at 3040 C. while a mixture of ethylene oxide ,(67.8 parts) and propylene oxide (89.3 parts) were added. During the latter half of the addition the temperature was allowed to rise to 60 C. and was maintained at 60 C. for 1% hours on completion of the addition. After removal of volatile products at 60 C. and 20 mm. presure the residual product consisted of 205.8 parts of an adduct of ethyl octynol with 7.07 molar proportions of ethylene oxide/ propylene oxide in approximately 1:1 molar ratio.

EXAMPLE 10 The adduct of Example 9 (102.9 parts) and boron trifiuoride etherate (0.75 part) were stirred at 60 C. while a mixture of ethylene oxide (33.9 parts) and propylene oxide (44.7 parts) was added. After further treatment as in Example 2 the residual product consisted of an adduct of ethyl octynol with 13.22 molar proportions of ethylene oxide/propylene oxide in approximately 1:1 molar ratio.

The adducts of the above examples were tested for inhibiting efficiency according to the following procedure.

A 40 cm. length of bright annealed mild steel, 16 mm. wide and 0.3 mm. thick, was degreased by immersion in boiling toluene, wiped dry with a clean dry absorbent duster, weighed accurately, and immersed in 14% hydrochloric acid containing the composition under test at C. for 3 minutes. The strip was withdrawn, washed under cold running water, immersed in dilute amomnia solution, washed under hot running water, immersed in acetone and wiped dry with a clean dry absorbent duster. The strip was then reweighed and the weight loss determined.

The percentage efliciency was calculated according to the following formula:

Percent efiiciency:

X wt. loss in uninhibited acid Wt. loss (grams) Percent efiicieney After After Initially 24 hrs. Initially 24 hrs.

Dosage, percent w./v.

The following were obtained.

Composition Uninhibited acid-..

Test No.

B B B B B 20 References Cited Ylene UNITED STATES PATENTS 2,327,053 8/1943 Marple et a1. 2606.5 2,380,185 7/1945 Marple et al. 2606.5 2,807,651 9/1957 Britton et al. 260-65 3,030,426 4/1962 Moseley et a1. 260--6.5 3,268,593 8/1966 Carpenter et al. 260-65 FOREIGN PATENTS 616,256 2/1949 Great Britain 2606.5 B

OTHER REFERENCES Petrov et al., Chem. Abst. 46 2992d 1952.

pentyl, HOWARD T. MARS, Primary Examiner each Y represents US. Cl. X.R. 252146 What we claim is: 1. A polyoxyalkylene derivative of an acet hol having the general formula:

CECE

wherein R represents methyl, ethyl, propyl and represents hydrogen, methyl or ethyl oxyethylene and oxypropylene in about a 1:1 ratio and n is an integer of from 4.68 to 15.6. 

